Pastor Emmanuel Momoh, who also works as a miner, discovered the 706-carat diamond in Kono district, the government said in a statement.

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He handed it over to President Ernest Bai Koroma, who thanked him for not smuggling it out of the country. The President pledged to reward him with some of the proceeds from the sale of the diamond.

The government plans to sell it to the highest bidder, the President said.

The gem may not be the largest ever found, but it's pretty close.

Last year, an uncut 1,109-carat diamond was auctioned in London -- the largest uncut diamond ever found.

The diamond discovered in Botswana was named Lesedi La Rona, meaning "Our Light" in the local Tswana language. It's surpassed in size only by the 3,106-carat "Cullinan Diamond" found in 1905 in South Africa. A cut of that diamond, known as the "First Star of Africa," now is part of British royal family's crown jewels.